Question - Light Switch Replacement.

Hello all

I'm new to the forum. We just purchased a flat and wanted to do a few simple DIY to the place. This forum has been extremely helpful!

I am replacing my light switches and sockets in my home from plastic to metal.

So far I haven’t come across too many issues with the simple switches as I am just making like-for-like replacements. No specific changes or additions. This is until I opened up the light switch socket in my main bedroom and saw a plethora of cables which I did not expect (see picture below).



To summarise - this is a 2-way switch that turns on three ceiling lights. They are currently:

• 1 x grey wire connected to the COM terminal
• 3 x brown wires connected to L1
• 1 x black wire and 1 x brown wire connected to L2
• 3 x blue wires connected to Wago slots
• 4 x earth wires connected to Wago slots
• 1 x earth wire where one end is connected to a Wago slot, and the other to the earth terminal in the metal box.

I was going to do a like-for-like replacement of these connections with the new switch. My concerns here are to do with earthing. Do I need to remove all of the earth wires from the Wago and connect them to the earth terminal on the metal face plate? (There is only one terminal on the face plate and I’m not sure if they will all fit). What should I do with the earth wire currently connected to the earth terminal in the metal box?

(And can anyone see any other issues?)

Or is this just a bit too complicated and I’ll have to wave the flag and call an electrician?

Many thanks for your time!

It seems like you have a "loop at switch" setup combined with 2 way switching.

Killer167 said:

Hello all
1 x grey wire connected to the COM terminal

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for the two way switching.

3 x brown wires connected to L1

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Probablly permanent live (3 conductors, one for the incoming supply, one out to the next item on the circuit and one for the two way switching).

1 x black wire and 1 x brown wire connected to L2

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Probablly the switch live (2 conductors, one going to the light and one as part of the two way switching)

3 x blue wires connected to Wago slots

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Neutrals.

I would leave the wagos as they are. As you say getting that many earth wires into a faceplate earth terminal is going to be an excercise in frustration.

You do need an earth wire to the metal faceplate. It is considered acceptable to earth the backbox from the faceplate via the screwsbut not vice-vesa. You could either disconnect the wire going to your backbox and attatch it to the faceplate or add a link wire from the backbox earth terminal to the faceplate.

plugwash said:

You do need an earth wire to the metal faceplate. It is considered acceptable to earth the backbox from the faceplate via the screwsbut not vice-vesa. You could either disconnect the wire going to your backbox and attatch it to the faceplate or add a link wire from the backbox earth terminal to the faceplate.

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Thanks so much for your response!

So the "link wire" would essentially just be another earth wire (or what I've seen people call "fly lead") with the yellow/green sheath that I can purchase from say, Amazon?

Killer167 said:

Thanks so much for your response!

So the "link wire" would essentially just be another earth wire (or what I've seen people call "fly lead") with the yellow/green sheath that I can purchase from say, Amazon?

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Or if have a spare length of three core flex, you could strip a piece of yellow/green from that.

have you got two blues going into one wago terminal? i thought you were only supposed to put one wire in each hole?

This is why I avoid wagos where I can.

There's never enough holes...

plugwash said:

You do need an earth wire to the metal faceplate. It is considered acceptable to earth the backbox from the faceplate via the screwsbut not vice-vesa. You could either disconnect the wire going to your backbox and attatch it to the faceplate or add a link wire from the backbox earth terminal to the faceplate.

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Hi, thanks for your help! Coming back to this comment - does it mean that it is fine in this case to just have a fly lead connected between the earth terminals of the metal box and the metal face plate? (i.e. no need to take any of the earth wires from the existing light circuit to connect to the face plate?)

You must earth the faceplate; it is not necessary to earth the backbox but it is just as well to do it.

Killer167 said:

Hi, thanks for your help! Coming back to this comment - does it mean that it is fine in this case to just have a fly lead connected between the earth terminals of the metal box and the metal face plate? (i.e. no need to take any of the earth wires from the existing light circuit to connect to the face plate?)

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You need an earth path from the earth conductors in the wiring to the metal faceplate which does not rely on the faceplate screws.

So if you leave all the existing wires in place and add a wire from the earth terminal in the backbox to the faceplate you are fine.

Brilliant, thanks all!